Methods and apparatuses for removing amines from extracted hydrocarbon streams

ABSTRACT

Methods and apparatuses for processing hydrocarbons are provided. In one embodiment, a method for processing a hydrocarbon stream includes feeding a hydrocarbon stream including amine and mercaptan to an extraction zone. The method includes contacting the hydrocarbon stream with an alkaline stream in the extraction zone to convert the mercaptan to a mercaptide. Further, the method includes contacting the hydrocarbon stream with water in the extraction zone to remove the amine from the hydrocarbon stream.

TECHNICAL FIELD

The technical field generally relates to methods and apparatuses forprocessing hydrocarbons, and more particularly relates to methods andapparatuses for removing contaminants from a hydrocarbon stream withalkaline and amine and for removing the alkaline and amine from thehydrocarbon stream.

BACKGROUND

Sour hydrocarbon streams are typically treated to remove mercaptans,such as by extraction processes. Mercaptans have traditionally beenremoved from hydrocarbon streams because of their malodorous scent. Sourhydrocarbon streams may also include acid gases such as carbon dioxide.Attempts have been made to remove acid gases from hydrocarbon streamsthrough the absorption of acid gases with amines.

In a typical liquid-liquid extraction process, caustic is used toconvert mercaptans to mercaptides. Hydrogen sulfide must be removed in aprewash vessel before extraction or the caustic will preferably reactwith the hydrogen sulfide in the extractor vessel and leave mercaptansin the hydrocarbon stream. Often, a liquid hydrocarbon stream is fed toan amine absorber column to be contacted with an amine, such asdiethanolamine, to absorb acid gases such as hydrogen sulfide and carbondioxide from the hydrocarbon stream. The hydrocarbon stream lean ofhydrogen sulfide and other acid gases is then prewashed in a prewashvessel containing liquid caustic to convert the remaining hydrogensulfide to sodium sulfide which is soluble in caustic. The hydrocarbonstream, depleted of hydrogen sulfide, flows through the extractionvessel and is subjected to counter-current flow of liquid caustic.Mercaptans in the hydrocarbon stream react with the caustic to yieldmercaptides. The mercaptides in the hydrocarbon stream are soluble inthe caustic. A product hydrocarbon stream lean in mercaptans may passoverhead from the extraction column. The mercaptide rich caustic exitsthe bottom of the extraction column.

The amine used to absorb acid gases may be soluble in the hydrocarbonstream. However, the product formed from the extraction process may berequired to be amine-free. Therefore, an amine removal process must beperformed. However, addition of a water wash to remove amine from thehydrocarbon product stream can add 10% or more to the installation costof an extraction process unit.

Accordingly, it is desirable to provide methods and apparatuses forremoving amines from extracted hydrocarbon streams. In addition, it isdesirable to provide methods and apparatuses that economically extractcontaminants from hydrocarbon streams. Furthermore, other desirablefeatures and characteristics will become apparent from the subsequentdetailed description and the appended claims, taken in conjunction withthe accompanying drawings and the foregoing technical field andbackground.

BRIEF SUMMARY

Methods and apparatuses for processing hydrocarbons are provided. In anexemplary embodiment, a method for processing a hydrocarbon streamincludes feeding a hydrocarbon stream including amine and mercaptan toan extraction zone. The method includes contacting the hydrocarbonstream with an alkaline stream in the extraction zone to convert themercaptan to a mercaptide. Further, the method includes contacting thehydrocarbon stream with water in the extraction zone to remove the aminefrom the hydrocarbon stream.

In another embodiment, a method for processing hydrocarbons includingfeeding a hydrocarbon stream containing sulfur compounds and acid gasesto a prewash zone containing amine to remove the acid gases. The methodincludes withdrawing a prewashed hydrocarbon stream from the prewashzone and feeding the prewashed hydrocarbon stream to an extraction zone.The method contacts the prewashed hydrocarbon stream with an alkalinestream in the extraction zone to convert mercaptans to mercaptides.Further, the method contacts the hydrocarbon stream with water in theextraction zone, wherein the water removes amine entrained in thehydrocarbon stream. The method includes withdrawing an extractedhydrocarbon stream from the extraction zone.

In accordance with another exemplary embodiment, an apparatus forprocessing a hydrocarbon stream is provided. The apparatus comprises anextraction vessel including an extraction section positioned below awash section. The apparatus also includes a hydrocarbon conduitconnected to the extraction vessel for delivering a hydrocarbon streamincluding a mercaptan and an amine for upward flow through theextraction section and through the wash section. An alkaline conduit isconnected to the extraction vessel for delivering an alkaline stream fordownward flow through the extraction section. A water conduit isconnected to the extraction vessel for delivering water for downwardflow through the wash section and through the extraction section. Theapparatus further includes an effluent outlet for removing the alkalinestream and the water from the extraction vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of methods and apparatuses for removing amines fromextracted hydrocarbon streams will hereinafter be described inconjunction with the following drawing figure wherein:

FIG. 1 is a schematic diagram of an apparatus for extractingcontaminants from a hydrocarbon stream with alkali and amine inaccordance with an embodiment; and

FIG. 2 is a schematic diagram of an apparatus for removing alkali andamine from the extracted hydrocarbon stream in accordance with anembodiment.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit the methods and apparatuses for processinghydrocarbon streams claimed herein. Furthermore, there is no intentionto be bound by any theory presented in the preceding background or thefollowing detailed description.

As described herein, methods and apparatuses are provided for removingamine and other aqueous soluble impurities, such as caustic, fromextracted hydrocarbon streams. In an exemplary embodiment, amine andalkaline are contacted with the hydrocarbon stream in an extraction zoneto facilitate removal of mercaptans and acid gases from the hydrocarbonstream. Then, the hydrocarbon stream passes through a wash section ofthe extraction zone where the hydrocarbon stream is contacted withwater. The water removes amine other aqueous soluble impurities in thehydrocarbon stream. The hydrocarbon stream also passes through acoalescer that removes any entrained alkaline in the hydrocarbon stream.Thereafter, the hydrocarbon stream exits the extraction zone,substantially free of amine and alkaline.

A general understanding of the method and apparatus claimed herein canbe obtained by reference to FIGS. 1 and 2. FIGS. 1 and 2 have beensimplified by the deletion of a large number of apparatuses customarilyemployed in a process of this nature such as vessel internals,temperature and pressure controls systems, flow control valves, recyclepumps, and the like that are not specifically required to illustrate theperformance of the method and apparatus. Although aqueous caustic ismentioned as the exemplary reagent for converting sulfur compounds,other aqueous alkaline solutions are contemplated.

Referring then to FIG. 1, an apparatus 8 is provided for removal ofcontaminants from a hydrocarbon stream 10. The hydrocarbon stream 10 maybe liquefied petroleum gas (LPG) or naphtha containing mercaptan sulfurand hydrogen sulfide. The hydrocarbon stream 10 is fed to an amineabsorber vessel 12. Amines 14 such as diethanolamine or monoethanolamineare fed to the amine absorber vessel 12. The amine absorber vessel 12contains a series of trays. The hydrocarbon stream 10 is introducedproximate the bottom of the amine absorber vessel 12 and the amines 14are introduced proximate the top of the amine absorber vessel 12 toallow counter-current contact of the amines 14 descending in the amineabsorber vessel 12 and the hydrocarbon stream 10 ascending through theamine absorber vessel 12. The amines 14 in the amine absorber vessel 12react with hydrogen sulfide to yield thiolamides. Typically, ahydrocarbon stream 10 containing approximately 100 to 100,000 weightparts per million (wppm) of hydrogen sulfide is reduced down toapproximately 15 to 50 wppm of hydrogen sulfide concentration in theamine absorber vessel 12. An amine effluent stream 16 rich inthiolamides exits the bottom of the amine absorber vessel 12 while thehydrocarbon effluent stream 18 exits the top of the amine absorbervessel 12 with a substantially reduced concentration of hydrogensulfide. Additionally, carbon dioxide or other acid gases that arepossibly present in the hydrocarbon stream 10 also react with the amines14 and are absorbed into the amine effluent stream 16 leaving the amineabsorber vessel 12.

A caustic recirculation conduit 20 joins the hydrocarbon effluent stream18 to allow an aqueous alkaline solution such as aqueous caustic and thehydrocarbon effluent stream 18 from the amine absorber vessel 12 to mixin combined stream 22 before entering an extraction vessel 24. Apressure differential indicator controller (PDIC) 26 maintains apressure drop across a control valve 28 such as 7 to 103 kilopascals(kPa) and preferably 28 to 55 kPa to ensure adequate mixing between theliquid caustic and the liquid hydrocarbon in the combined stream 22.Alternatively, a static mixer can be used for adequate mixing.

As shown, the premixed hydrocarbon and aqueous caustic combined stream22 enters the extraction vessel 24. The extraction vessel 24 comprises alower prewash zone 30 and an upper extraction zone 32 separated by animperforate, downwardly convexed baffle 34. As used herein, the term“zone” can refer to an area including one or more equipment items and/orone or more sub-zones. Equipment items can include one or more reactorsor reactor vessels, heaters, exchangers, pipes, pumps, compressors, andcontrollers. Additionally, an equipment item, such as a reactor, dryer,or vessel, can further include one or more zones or sub-zones. Theextraction zone 32 is directly above the prewash zone 30 and both zones30 and 32 preferably share at least one common wall 33. The prewash zone30 includes a coalescer 36 proximate a top of the prewash zone 30. Thecombined stream 22 is fed into the prewash zone 30 proximate a bottom ofthe prewash zone 30.

In the prewash zone 30, an aqueous alkaline solution such as caustic offrom about 2 to about 15 weight percent (wt %), such as from about 3 toabout 12 wt %, for example from about 6 to about 12 wt %, reacts withany remaining hydrogen sulfide to yield a sulfide salt such as sodiumsulfide. The higher density aqueous caustic and sulfides dissolvedtherein gravitate to the bottom of the prewash zone 30 while thehydrocarbon depleted of hydrogen sulfide rises to the top of the prewashzone 30. A coalescer 36 serves to gather together smaller droplets ofcaustic that rise in the prewash zone 30 to give them sufficient weightto begin descending through the prewash zone 30 with the rest of thecaustic. The prewash zone 30 can also be used to remove COS from thehydrocarbon by reacting it with a solvent composed of a mixture of amineand alkaline. In an exemplary embodiment, the amine is from about 5 toabout 20 wt % of the solution and the caustic is from about 6 to about12 wt %.

A transfer conduit 38 has an inlet in communication with the prewashzone 30 proximate a top of the prewash zone 30 above the coalescer 36and an outlet in communication with the extraction zone 32 proximate abottom of the extraction zone 32. The higher density caustic pushes thelower density hydrocarbon up through the transfer conduit 38 without theneed for a pump. A pump 42 pumps spent caustic out of the bottom of theprewash zone 30 through the recirculation conduit 20. Spent caustic iswithdrawn from the recirculation conduit 20 through a line 44 regulatedby a control valve 46. The flow rate of caustic through the controlvalve 46 is automatically controlled by a level indicator controller(LIC) 48 which monitors the level of caustic in the prewash zone 30 atthe hydrocarbon-caustic interface. The LIC 48 sensing the level ofcaustic in the prewash zone 30 signals a setting for the control valve46 relative to fully open to bring the level of the caustic in theprewash zone 30 to a desired, preset level. Accordingly, spent causticis continuously withdrawn from the prewash zone 30 through the line 44via the recirculation conduit 20. The spent caustic withdrawn throughthe line 44 may be sent to a spent caustic degassing drum (not shown)which allows volatile hydrocarbons to evaporate off of the top of thedrum before the spent caustic descends out of the drum to treatment.Regenerated caustic in a line 50 is continuously fed to the causticrecirculation conduit 20 and hence to the prewash zone 30 at a flow rateregulated by a control valve 52 governed by a flow rate controller (FRC)98. Additionally, water 54 is added to the caustic recirculation conduit20.

An aqueous alkaline solution such as aqueous caustic in the extractionzone 32 has a concentration of from about 12 to about 19 wt %), such asfrom about 13 to about 16 wt %. A hydrocarbon stream substantiallydevoid of hydrogen sulfide exits the outlet of the transfer conduit 38into the extraction zone 32. Mercaptans in the extraction zone 32 reactwith the caustic to yield sodium mercaptides and water. The lowerdensity hydrocarbons rise to the top of the extraction zone 32 while theaqueous caustic and mercaptides dissolved in the aqueous caustic sink tothe bottom of the extraction zone 32 where it collects at theimperforate, downwardly convexed baffle 34. The hydrocarbon rises to acoalescer 58 comprising a mesh blanket having a thickness of about 61centimeters (cm) that coalesces smaller caustic droplets carried to thetop of the extraction zone 32 with hydrocarbon because of their smallersize. The coalescer 58 coalesces smaller droplets of caustic together toform larger droplets that will tend to sink back to the bottom of theextraction zone 32. Treated hydrocarbon substantially devoid ofmercaptans and mercaptides exits the extraction zone 32 via a productconduit 60.

Spent caustic rich in mercaptides is withdrawn through a drain at thelowermost portion of the downwardly convexed baffle 34 through a line62. The line 62 actually extends through the prewash zone 30 above thecoalescer 36 and through the common wall 33 thereof.

A line 64 adds oxidation catalyst to the line 62. A specific mercaptanoxidation catalyst is not required. Many suitable catalysts are known inthe art. One preferred class of catalyst comprises sulfonated metalphthalocyanine. A particularly preferred sulfonated metal phthalocyanineis highly monosulfonated cobalt phthalocyanine or other phthalocyaninecatalysts. Additional dipolar type catalysts are suitable for use in analkaline contacting solution. Typically, the oxidation catalyst in theaqueous alkaline solution will have a concentration of from about 10 toabout 500 wppm, such as a concentration of about 200 wppm. The spentcaustic stream with added catalyst may be heated in an indirect heatexchanger with low pressure stream as a heat exchange fluid in a heater66. The heater 66 may heat the spent aqueous caustic from about 38° C.to about 43° C. Air sufficient to oxidize the mercaptides is added tothe spent caustic stream in the line 62 through a line 68 to form anoxidizer feed line 70. The spent aqueous caustic and air mixture isdistributed into an oxidation vessel 72. In the oxidation vessel 72, thesodium mercaptides catalytically react with oxygen and water to yieldcaustic and organic disulfides. Rashig rings or other particulatepacking in the oxidation vessel 72 may increase the surface area thereinto improve contact with the catalyst. An exit conduit 74 withdrawseffluent from a top of the oxidation vessel 72. The effluent from theoxidation vessel 72 comprises three phases including an air phase, aliquid disulfide phase and a liquid aqueous caustic phase.

The exit conduit 74 carries the effluent from the oxidation vessel 72 toa disulfide separator 76 comprising a vertical section 78 and ahorizontal section 80. Once settled in the separator, the air phaseexits the top of the vertical section 78 through a line 82. The twoliquid phases settle in the horizontal section 80 of the disulfideseparator 76. The lighter disulfide phase exits the top of thehorizontal section 80 through a line 84. The disulfide effluent from thedisulfide separator 76 is carried by the line 84 to a sand filter 86 tocoalesce and separate any traces of caustic and is removed from theprocess through a line 88. Heavier regenerated caustic exits the bottomof the horizontal section 80 through the line 90. The vertical section78 of the disulfide separator 76 includes carbon Rashig rings or otherparticulate packing to increase the surface area such that liquidentrained in the air is knocked out of entrainment and prevented fromexiting through the line 82. A portion of the horizontal section 80 ofthe disulfide separator 76 includes anthracite coal or other material toserve as a coalescer. Caustic droplets contained in the disulfide phasewill be coalesced into larger, heavier droplets that will fall down tothe heavier aqueous caustic phase to exit the inlet to the line 90instead of the inlet to the line 84.

The line 90 carrying regenerated caustic splits into two lines 92 and50. The line 92 carries regenerated caustic to the extraction zone 32 ata rate regulated by a control valve 94 governed by a flow ratecontroller (FRC) 96. The line 50 carries regenerated caustic to thecaustic recirculation conduit 20 at a flow rate regulated by the controlvalve 52 governed by the FRC 98. FRC 96 and FRC 98 measure the flow rateof caustic in their respective lines 92 and 50 and signal the controlvalves 52 and 94, a setting relative to fully open to obtain a desiredinput flow rate. The desired input flow rate is determined to obtain adesired caustic concentration in the respective section of theextraction vessel 24.

The pressure in the amine absorber vessel 12 and in the extractionvessel 24 is maintained by regulating the flow of hydrocarbon from theextraction zone 32 in the product conduit 60 by a control valve 61governed by a pressure indicator controller (PIC) 63 that monitors thepressure in the product conduit 60. The pressure should preferably bekept at a level to ensure that the hydrocarbon remains in a liquefiedstate. This pressure typically ranges from about 517 to about 2758 kPa.The temperature of the hydrocarbon streams may be maintained at atemperature of about 35° C. to about 40° C. The heater 66 raises thetemperature of the spent caustic to from about 40° C. to about 45° C.before it enters the oxidation vessel 72 in the line 70. The oxidationreaction is exothermic which results in an increase in the temperatureof the effluent in the exit conduit 74 typically not to exceed 57° C.Hence, the temperature in the disulfide separator 76 may be less than57° C. The pressure in the oxidation vessel 72 and in the disulfideseparator 76 may be maintained from about 345 to about 448 kPa in theline 82 by a control valve 85 regulated by a pressure indicatorcontroller (PIC) 87 monitoring the pressure in the line 82.

FIG. 1 illustrates an embodiment in which alkali and amines are used toremove contaminants such as mercaptans and acid gases from a hydrocarbonstream 10. FIG. 2 illustrates an apparatus 100 including additionalcomponents that may be used with the apparatus 8 of FIG. 1 or with otherapparatuses to remove the alkali and amines from the extractedhydrocarbon stream.

In FIG. 2, the apparatus 100 receives a hydrocarbon stream 102. Thehydrocarbon stream 102 may be the hydrocarbon stream substantiallydevoid of hydrogen sulfide that exits the outlet of the transfer conduit38 in FIG. 1. More generally, the hydrocarbon stream 102 is ahydrocarbon stream that includes amine and mercaptans. For example, thehydrocarbon stream 102 may include about 10 wppm to about 50 wppm ofamine. An exemplary hydrocarbon stream 102 is prewashed LPG. As shown,the hydrocarbon stream 102 is introduced into a lower section 104 of anextraction zone 106. In an exemplary embodiment, the extraction zone 106is contained by a column 108 such as extraction vessel 24 of FIG. 1.Further, the extraction zone 106 may be similar or the same asextraction zone 32 of FIG. 1 and positioned over a prewash zone, such asprewash zone 30.

The hydrocarbon stream 102 moves upward through contact trays 110 in thelower section 104 of the extraction zone 106. An exemplary lower section104 of the extraction zone 106 includes from about 7 to about 12 trays110. At each tray 110 in the lower section 104, the hydrocarbon stream102 contacts an alkaline stream 112 that is introduced to the extractionzone 106 proximate the top of the lower section 104 of the extractionzone 106, such as above the uppermost tray 110 in the lower section 104of the extraction zone 106. During contact between the alkaline stream112 and the hydrocarbon stream 102, mercaptans react with the alkalinestream 112 to yield sodium mercaptides and water. The lower densityhydrocarbon stream 102 rises to the top of the lower section 104 of theextraction zone 106 while the alkaline stream 112 and mercaptidesdissolved in the alkaline stream 112 sink to the bottom of the lowersection 104 of the extraction zone 106.

The hydrocarbon stream 102, substantially devoid of mercaptans andhydrogen sulfides, passes from the lower section 104 of the extractionzone 106 to an upper section 114 of the extraction zone 106.Specifically, the hydrocarbon stream 102 moves above the entry point ofthe alkaline stream 112. A stream of water 116 is fed into the uppersection 114 of the extraction zone 106, proximate the top of the uppersection 114 of the extraction zone 106. Specifically, the water 116 isintroduced above the uppermost tray 110 in the upper section 114 of theextraction zone 106. In an exemplary embodiment, the upper section 114of the extraction zone 106 includes from about 2 to about 4 trays 110.

The water 116 move downward through the upper section 114 of theextraction zone 106. As the water 116 contacts the hydrocarbon stream102 in the upper section 114 of the extraction zone 106, it absorbsamine from the hydrocarbon stream 102. As a result, the hydrocarbonstream 102 exiting the upper section 114 of the extraction zone 106 issubstantially devoid of amine. For example, after passing through theupper section 114 of the extraction zone 106, the hydrocarbon stream 102may include less than about 5 wppm amine, such as less than about 2 wppmamine, for example less than 1 wppm amine or no amine

As shown, the hydrocarbon stream 102 than passes through a coalescer120. The coalescer 120 may be the same or similar to the coalescer 58 ofFIG. 1. For example, the coalescer 120 may include a mesh blanket havinga thickness of about 61 cm that coalesces smaller alkaline dropletscarried to the top of the extraction zone 106 with the hydrocarbonstream 102 because of their smaller size. The water 116 may beintroduced below the coalescer 120 in the extraction zone 106. Thecoalescer 120 coalesces smaller droplets of alkaline together to formlarger droplets that will tend to sink back to the bottom of theextraction zone 106. A treated hydrocarbon stream 122, such as treatedLPG, substantially devoid of mercaptans, mercaptides, alkali, and amineexits the extraction zone 106.

The exemplary extraction zone 106 is operated at a temperature of fromabout 26° C. to about 49° C., such as from about 32° C. to about 43° C.Further, the exemplary extraction zone 106 is operated at a pressure offrom about 517 kPa to about 2758 kPa, such as from about 690 kPa toabout 2070 kPa.

As shown, an effluent stream 124 of alkaline solution rich inmercaptides exits the bottom of the extraction column 108.Alternatively, the effluent stream 124 may exit through a side outletabove an integral prewash zone as in FIG. 1. Air 126 sufficient tooxidize the mercaptides is added to the effluent stream 124 before theeffluent stream 124 is heated by heater 128 to a temperature of about38° C. to about 49° C. Then, the effluent stream 124 is fed to anoxidation unit 130, similar to or the same as oxidation vessel 72 ofFIG. 1.

At the oxidation unit 130, sodium mercaptides catalytically react withoxygen and water to yield caustic and organic disulfides. The oxidizedeffluent 132 then passes from the top of the oxidation unit 130 to adisulfide separator 134, similar to or the same as disulfide separator76 of FIG. 1.

After settling in the disulfide separator 134, spent air 136 exist thetop of a vertical section of the disulfide separator 134. A lighterliquid phase of disulfide 138 exits the top of a horizontal section ofthe disulfide separator 134. A heavier liquid phase of alkali forming arecovered alkaline stream 140 exits the bottom of the horizontal sectionof the disulfide separator 134.

The recovered alkaline stream 140 is pumped by pump 142 to a dehydrationunit 144. Alternatively, the dehydration unit 144 may be positionedupstream of pump 142 to allow dehydration at lower pressure. At thedehydration unit 144, the water content of the recovered alkaline stream140 is reduced. Specifically, the recovered alkaline stream 140 mayinclude water introduced into the extraction zone 106 at water stream116 and have a reduced alkaline content. In an exemplary embodiment, thedehydration unit 144 includes a water balance column operated at about60° C. to about 70° C. As a result, the alkaline stream 112 is formedwith a selected water content and alkali content. For example, thealkaline stream 112 may have a water content of about 85 wt % to about89 wt % and an alkaline concentration of about 11 wt % to about 15 wt %.

In cases where amine builds up in the circulating alkaline stream 112 tounacceptable amounts, the circulating alkaline stream may be bled orpurged and fresh alkaline solution may be added. For example, thealkaline stream may be bled or purged when the amine concentrationreaches about 5 wt %.

The apparatuses and methods described herein provide for the removal ofmercaptans and acid gases from hydrocarbon streams. Such removal isperformed with alkali and amine. The apparatuses and methods describedherein further provide for the removal of the alkaline and amine fromthe product stream formed by extraction. Further, the apparatuses andmethods described herein remove alkaline and amine within an extractionzone, and more specifically, within an extraction vessel withoutrequiring use of additional vessels. As a result, unit costs arereduced.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration of theclaimed subject matter in any way. Rather, the foregoing detaileddescription will provide those skilled in the art with a convenient roadmap for implementing an exemplary embodiment or embodiments. It beingunderstood that various changes may be made in the function andarrangement of elements described in an exemplary embodiment withoutdeparting from the scope set forth in the appended claims.

What is claimed is:
 1. A method for processing a hydrocarbon stream, themethod comprising: feeding a hydrocarbon stream including amine andmercaptan to an extraction zone; contacting the hydrocarbon stream withan alkaline stream in the extraction zone to convert the mercaptan to amercaptide; and contacting the hydrocarbon stream with water in theextraction zone to remove the amine from the hydrocarbon stream.
 2. Themethod of claim 1 further comprising removing an effluent from theextraction zone; separating a recovered alkaline stream from theeffluent; and dehydrating the recovered alkaline stream to form thealkaline stream.
 3. The method of claim 1 further comprising:withdrawing the hydrocarbon stream from the extraction zone; and passingthe hydrocarbon stream through a coalescer to remove alkaline componentsfrom the hydrocarbon stream before withdrawing the hydrocarbon streamfrom the extraction zone.
 4. The method of claim 1 wherein theextraction zone includes an extraction section positioned below a washsection, wherein contacting the hydrocarbon stream with the alkalinestream comprises contacting the hydrocarbon stream with the alkalinestream in the extraction section, and wherein contacting the hydrocarbonstream with water comprises contacting the hydrocarbon stream with waterin the wash section.
 5. The method of claim 4 wherein the hydrocarbonstream flows upward through the extraction section and through the washsection, and wherein the method further comprises: feeding the water tothe wash section, wherein the water flows downward through the washsection and through the extraction section; and feeding the alkalinestream to the extraction section, wherein the alkaline stream flowsdownward through the extraction section.
 6. The method of claim 1further comprising removing an effluent including the alkaline stream,the mercaptide, the water, and the amine from the extraction zone. 7.The method of claim 6 further comprising: oxidizing the effluent andconverting the mercaptide to disulfide; and separating the effluent toremove the disulfide from a recovered alkaline stream.
 8. The method ofclaim 7 further comprising: dehydrating the recovered alkaline stream toform the alkaline stream; and feeding the alkaline stream to theextraction zone to contact the hydrocarbon stream therein.
 9. The methodof claim 1 wherein: feeding the hydrocarbon stream including amine andmercaptan to the extraction zone comprises feeding the hydrocarbonstream to the extraction zone in an extraction vessel; contacting thehydrocarbon stream with the alkaline stream in the extraction zonecomprises contacting the hydrocarbon stream with the alkaline stream inthe extraction vessel; and contacting the hydrocarbon stream with waterin the extraction zone comprises contacting the hydrocarbon stream withwater in the extraction vessel.
 10. The method of claim 1 whereinfeeding a hydrocarbon stream including amine and mercaptan to theextraction zone comprises feeding a stream of liquefied petroleum gas tothe extraction zone.
 11. A method for processing a hydrocarbon stream,the method comprising: feeding a hydrocarbon stream containing sulfurcompounds and acid gases to a prewash zone containing amine to removethe acid gases; withdrawing a prewashed hydrocarbon stream from theprewash zone; feeding the prewashed hydrocarbon stream to an extractionzone; contacting the prewashed hydrocarbon stream with an alkalinestream in the extraction zone to convert mercaptans to mercaptides;contacting the hydrocarbon stream with water in the extraction zone,wherein the water removes amine entrained in the hydrocarbon stream; andwithdrawing an extracted hydrocarbon stream from the extraction zone.12. The method of claim 11 further comprising: removing an effluent fromthe lower section of the extraction zone; separating the effluent toform a recovered alkaline stream; dehydrating the recovered alkalinestream to form the alkaline stream; and feeding the alkaline stream tothe lower section of the extraction zone to contact the prewashedhydrocarbon stream therein.
 13. The method of claim 11 wherein theprewashed hydrocarbon stream flows upward through the extraction zone,wherein contacting the prewashed hydrocarbon stream with the alkalinestream comprises contacting the prewashed hydrocarbon stream with thealkaline stream in a lower section of the extraction zone, and whereincontacting the prewashed hydrocarbon stream with water comprisescontacting the hydrocarbon stream with water in an upper section of theextraction zone.
 14. The method of claim 13 further comprising: feedingwater to the upper section of the extraction zone, wherein the waterflows downward through the extraction zone; feeding the alkaline streamto the lower section of the extraction zone, wherein the alkaline streamflows downward through the extraction zone; and removing an effluentcomprising the water, the alkaline stream, the mercaptides, and theamine from an outlet adjacent the lower section of the extraction zone.15. The method of claim 14 further comprising passing the extractedhydrocarbon stream through a coalescer above the upper section of theextraction zone to remove alkaline components from the extractedhydrocarbon stream before withdrawing the extracted hydrocarbon streamfrom the extraction zone.
 16. The method of claim 14 further comprising:adding air to the effluent; oxidizing the effluent and converting themercaptides to disulfides; and separating the effluent to form a streamof air, a stream of disulfides and a recovered alkaline stream.
 17. Themethod of claim 16 further comprising: dehydrating the recoveredalkaline stream to form the alkaline stream with a higher alkaliconcentration than the prewash zone; and feeding the alkaline stream tothe lower section of the extraction zone to contact the prewashedhydrocarbon stream therein.
 18. The method claim 11 wherein theextraction zone is directly above the prewash zone and whereinwithdrawing the prewashed hydrocarbon stream from the prewash zone andfeeding the prewashed hydrocarbon stream to the extraction zonecomprises passing the prewashed hydrocarbon stream from the prewash zoneto extraction zone via a conduit.
 19. The method of claim 11 wherein:feeding the hydrocarbon stream comprises feeding the hydrocarbon streamat a location proximate a bottom of the prewash zone; withdrawing theprewashed hydrocarbon stream from the prewash zone comprises withdrawingthe prewashed hydrocarbon stream at a location proximate a top of theprewash zone; feeding the prewashed hydrocarbon stream to the extractionzone comprises feeding the prewashed hydrocarbon stream to a lowersection of the extraction zone; and the method further comprises feedingthe water to an upper section of the extraction zone.
 20. An apparatusfor processing a hydrocarbon stream, the apparatus comprising: anextraction vessel including an extraction section positioned below awash section; a hydrocarbon conduit connected to the extraction vesselfor delivering a hydrocarbon stream including a mercaptan and an aminefor upward flow through the extraction section and through the washsection; an alkaline conduit connected to the extraction vessel fordelivering an alkaline stream for downward flow through the extractionsection; a water conduit connected to the extraction vessel fordelivering water for downward flow through the wash section and throughthe extraction section; and an effluent outlet for removing the alkalinestream and the water from the extraction vessel.